This invention relates to electrostatographic xerographic type reproduction machines, and more particularly, to an improved control system for such machines.
The advent of higher speed and more complex copiers and reproduction machines has brought with it a corresponding increase in the complexity in the machine control wiring and logic. While this complexity manifests itself in many ways, perhaps the most onerous involves the inflexibility of the typical control logic/wiring systems. For as can be appreciated, simple unsophisticated machines with relatively simple control logic and wiring can be altered and modified easily to incorporate changes, retrofits, and the like. Servicing and repair of the control logic is also fairly simple. On the other hand, some modern high speed machines, which often include sorters, a document handler, choice of copy size, multiple paper trays, jam protection and the like have extremely complex logic systems making the most minor changes and improvements in the control logic difficult, expensive and time consuming. And servicing or repairing the machine control logic may similarly entail substantial difficulty, time and expense.
To mitigate problems of the type alluded to, a programmable controller may be used, enabling changes and improvements in the machine operation to be made through the expediency of reprogramming the controller. However, the control data which operates the machine and which is stored in the controller memory pending use, must be transferred to the various machine components at the proper time and in the correct sequence without unduly interfering with or introducing unnecessarily upon the other essential functions and operations of the controller.
It is therefore an object of the present invention to provide a new and improved control system for electrostatographic type reproduction machines.
It is a further object of the present invention to provide a self-testing system for the controller of a reproduction machine.
It is an object of the present invention to provide a system for checking the operating condition of the controller in a reproduction machine both before start-up of the machine and periodically during machine operation.
It is an object of the present invention to provide an improved arrangement for verifying the operating integrity of a reproduction machine controller and terminating machine operation in the event a fault is found.
It is a further object of the present invention to provide a system for checking the operational integrity of a copier controller and identifying, in the event a malfunction is found, the offending controller part.
The invention relates to a method for checking the integrity of the memory section of a controller for an electrostatic type reproduction machine, the steps comprising: totalizing the content of said memory; comparing the memory total with a predetermined checksum; and preventing operation of said machine when said memory total is different than said predetermined checksum.